TOYOTA PREVIA 91-97 REPAIR MANUAL

GENERAL INFORMATION AND MAINTENANCE 1-

FASTENERS, MEASUREMENTS AND CONVERSIONS

Bolts, Nuts and Other Threaded Retainers

I See Figures 20, 21, 22 and 23

Although there are a great variety of fasteners found in the modern car or
truck, the most commonly used retainer is the threaded fastener (nuls,
bolts, screws, studs, etc). Most threaded retainers may be reused, provided
that they are not damaged in use or during the repair. Some retainers (such
as stretch bolts or torque prevailing nuts) are designed to deform when
tightened or in use and should not be reinstalled.

Whenever possible, we will note any special retainers which should

be replaced during a procedure. But you should always inspect the con-

dition of a retainer when it is removed and replace any that show signs

of damage. Check all threads for rust or corrosion which can increase

the torque necessary to achieve the desired clamp load for which that

fastener was originally selected. Additionally, be sure that the driver sur-

face of the fastener has not been compromised by rounding or other

damage. In some cases a driver surface may become only partially

rounded, allowing the driver to catch in only one direction. In many of

these occurrences, a fastener may be installed and tightened, but the dri-

POZIDRIVE PHILLIPS RECESS TORX CLUTCH RECESS

INDENTED HEXAGON HEXAGON TRIMMED

Fig. 20 Here are a few of the most common screw/bolt driver styles

HEXAGON WASHER HEAD

TCCS

BOLTS

GRADE 0 GRADE 2 GRADE 5 GRADE • GRADE 7 GRADE I ALLEN CARRIAGE

NUTS

CASTLE

(CASTELLATED)

SCREWS

LOCKWASHERS

EXTERNAL

TOOTH

STUD

HUD

Fig. 21 There are many different types of threaded retainers found on vehicles